Clinical Applications of Optical Coherence Tomography Angiography in Ocular Oncology: Pearls and Pitfalls

Abstract

Background: Optical coherence tomography angiography (OCTA) is a valuable imaging tool for the diagnosis of several retinal and choroidal diseases. Its role in ocular oncology is clinically promising but still controversial. In this review, we report the main applications and limits of the use of OCTA for the study of intraocular tumors.

Summary: OCTA allows a rapid, safe, low-cost, and high-resolution visualization of the retinal and choroidal vasculature. Attempts have been made to use this technology in ocular oncology to differentiate benign and malignant lesions and to assist physicians in the evaluation and monitoring of post-treatment complications. Main limitations include failure in correct segmentation due to the tumor inner profile or thickness, poor penetration of the laser into the lesion, masking effect from overlying fluid, media opacities and poor fixation.

Key messages: The main applications of OCTA in ocular oncology consist of the documentation of tumor-associated choroidal neovascularizations and the study of vascular changes following tumor treatments. In particular, the diffusion of wide-field protocols makes OCTA suitable for the diagnosis and follow-up of radiation chorio-retinopathy, allowing a detailed visualization of both macular and peripheral ischemic changes. Optimistically, future innovations in OCTA technology may offer new perspectives in the diagnosis and follow-up of intraocular tumors.

Keywords: Angiography; Intraocular tumors; Optical coherence tomography angiography; Uveal melanoma.

Fig. 1

Fundus photography (a, e, i, o, s) and the corresponding OCTA image of the superficial retinal plexus (b, f, l, p, t), choriocapillaris (c, g, m, q), and avascular zone (u) in 5 eyes with choroidal nevi. Superficial retinal plexus typically looks preserved apart from a possible reduction in vascular density for the thickest tumors or in case of chronic changes occurring at the level of the outer retina or RPE (l). Study of the choriocapillaris may reveal different patterns including a predominant hyporeflective core (flow voids) with a surrounding hyperreflective ring (c, g) or a diffuse hyperreflectivity (q). The increased reflectivity occurring at this level should be considered an artifact rather than a real increase in vascular flow; this phenomenon is mainly secondary to the well-known high reflectivity of choroidal nevi in OCT and is confirmed by the analysis of B-scans with flow overlay (d, h, n, r, v). Differently, in case of RPE atrophic changes (case 2; e–h) and amelanotic/partially pigmented tumors (case 3; i–n), increased light transmission allows for the detection of flow signal within the tumor likely corresponding to normal choroidal vasculature. o–v Two young patients presenting with a choroidal nevus complicated by subretinal fluid: in these cases, OCTA should be used to evidence a type II CNVm (u, v) or to confirm the absence of the CNV (q, r). RPE, retinal pigment epithelium; CNVm, choroidal neovascular membrane.

Fig. 2

Fundus photography (a, d, g, l), OCTA (b, e, h, m), and OCT B-scan with an angio overlay (c, f, i, n) in 4 patients presenting with choroidal melanoma. SS-OCTA imaging in en-face visualization successfully reveals tumor-intrinsic microcirculation in a pigmented melanoma with an epicenter on the superotemporal vascular arcade and measuring 4.0 mm in thickness (b), in an 8.9-mm choroidal melanoma with massive exudative retinal detachment (e) and in a 3.3-mm amelanotic melanoma (h). Interestingly, no intrinsic vascularization can be reliably disclosed in the last case (m) despite a tumor measuring only 1.9 mm in thickness, minor subretinal exudation, and good quality of the imaging.

Fig. 3

Fundus photography (a) and wide-field OCTA (23 × 20 mm with flow analysis at the level of the inner choroid) (b) of the left eye of a 47-year-old female suffering from breast adenocarcinoma complicated by choroidal metastases. c 6 × 6 mm OCTA volume performed temporally to the macula showing a well-defined choroidal mass with diffuse decrease in flow signal secondary to diffuse choroidal infiltration visible also on the B-scan with a flow overlay (d); few vascular structures can be noticed within the lesion. Inferiorly to the main tumor, 2 sub-millimetric metastases can be recognized and corresponding with 2 areas of focal flow void on the B-scan (e). f–i Fundus photography (f) and ICGA (g) in a patient presenting with a CCH. Differently from ICGA where tumor margins can be clearly defined, OCTA typically does not offer a clear visualization of the hemangioma especially on en-face visualization (h); within a region of global hyporeflectivity, few large, dense, vascular trunks can be observed. On the contrary, a B-scan with a flow overlay clearly highlights the presence of preserved flow at the level of the choriocapillaris and inner choroid without the typical compression occurring in melanocytic tumors and metastases. l–o Fundus images (l, n) and OCTA analysis (m, o) of 2 patients suffering of choroidal osteoma; OCTA (m, o) displays tumor intrinsic vasculature in both cases and reveals the presence of a secondary CNVm (o). CNVm, choroidal neovascular membrane.

Fig. 4

a–c FA acquired using the Heidelberg 102° wide-field noncontact lens (a), 6 × 6 OCTA volume centered on the macula (b) and montage of two 23 × 20 mm volumes performed using an SS-OCTA device (c) in a case of a circumpapillary melanoma successfully treated using proton beam radiotherapy. Wide-field FA (a) displays parafoveal leakage, optic nerve staining, and peripheral areas of hyperfluorescence; OCTA (b, c) allows a detailed examination of the foveal and parafoveal region showing diffuse dropout of the superficial retinal capillary plexus nasally to the fovea but also focal areas of retinal-nonperfusion and vascular remodeling (arrowheads) in the extreme nasal, inferior, and temporal periphery (c). d–g Fundus photography (d), wide-field FA (e), and OCTA showing retinal (f) and choriocapillaris/choroidal flow (g), respectively, in a patient previously treated with brachytherapy and sectoral photocoagulation for an inferior choroidal melanoma. OCTA allows separate monitoring of radiation-related changes occurring at the level of the retina and choroid; OCTA scans were in this case acquired using a single 23 × 20 mm volume centered on the fovea.